Morchella


Morchella, the true morels, is a genus of edible sac fungi closely related to anatomically simpler cup fungi in the order Pezizales. These distinctive fungi have a honeycomb appearance due to the network of ridges with pits composing their caps.
Morels are prized by gourmet cooks, particularly in Catalan and French cuisine, but can be toxic if consumed raw or undercooked. Due to difficulties in cultivation, commercial harvesting of wild morels has become a multimillion-dollar industry in the temperate Northern Hemisphere, in particular North America, Turkey, China, the Himalayas, India, and Pakistan where these highly prized fungi are found in abundance.
Typified by Morchella esculenta in 1794, the genus has been the source of considerable taxonomical controversy throughout the years, mostly with regard to the number of species involved, with some mycologists recognising as few as three species and others over thirty. Current molecular phylogenetics suggest there might be over seventy species of Morchella worldwide, most of them exhibiting high continental endemism and provincialism.
The genus is currently the focus of extensive phylogenetic, biogeographical, taxonomical and nomenclatural studies, and several new species have been described from Australia, Canada, Cyprus, Israel, Spain, and Turkey.

Description

Morels resemble a honeycomb due to the network of ridges with pits composing their caps. Morels have a convoluted head/cap, and are varied in shape and habitat.

Similar species

When foraging for morels, one must be absolutely sure of identification. There are many look-alikes often referred to as "false morels", most notably Gyromitra. These also include members of the most closely related genus, Verpa, which are highly poisonous. Other mushrooms can also be mistaken for morels, including some species of stinkhorns, or Phallaceae, which have a similarly shaped cap but a distinctive foul odor. It is important to take care when harvesting and identifying mushrooms, particularly morels.
The key morphological features distinguishing false morels from true morels are as follows:
  • Gyromitra species often have a "wrinkled" or "cerebral" appearance to the cap due to multiple wrinkles and folds, rather than the honeycomb appearance of true morels due to ridges and pits.
  • The caps of morels come in a range of colors including white, grey, black, brown, and yellow. Gyromitra esculenta has a cap that is usually reddish-brown in colour, but sometimes also chestnut, purplish-brown, or dark brown.
  • True morels are always hollow when sliced lengthwise, whereas Gyromitra species are typically chambered in longitudinal sections, while Verpa species contain a cottony substance inside their stem. The easiest way to distinguish Verpa species from Morchella species is to slice them longitudinally.
  • The caps of Verpa species are attached to the stem only at the apex, unlike true morels which have caps that are attached to the stem at, or near the base of the cap.

    Taxonomy

The fruit bodies of Morchella species are highly polymorphic, varying in shape, color, and size. While in many cases they do not exhibit clear-cut distinguishing features microscopically, this has historically contributed to uncertainties in taxonomy. Discriminating between the various taxa described is further hindered by uncertainty over which of these are truly biologically distinct. Remarkably, some authors in the past had suggested that the genus contains as few as 3 to 6 species, while others recognised as many as 34. Efforts to clarify the situation and re-evaluate old classical names in accordance to current phylogenetic data have been challenging, due to vague or ambiguous original descriptions and loss of holotype material. In 2012, the simultaneous description of several new taxa from Europe by Clowez and North America by Kuo and colleagues resulted in several synonyms further complicating matters, until a transatlantic study by Richard and colleagues resolved many of these issues in 2014. The genus is currently undergoing extensive re-evaluation with regard to the taxonomic status of several species.

Early taxonomic history

Morchella Dill. ex Pers. : Fr. was typified by Christiaan Hendrik Persoon in 1794, with Morchella esculenta designated as the type species for the genus. Among early pioneers who took an interest in the genus, were mycologists Julius Vincenz von Krombholz and Émile Boudier, who, in 1834 and 1897 respectively, published several species and varieties, accompanied by meticulously illustrated iconographic plates. The seminal taxon Morchella elata, whose true identity still remains unresolved, was described by Elias Fries in 1822, from a fir forest in Sweden. Other classical, early-proposed names include Morchella deliciosa, also described by Fries in 1822, Morchella semilibera, the half-free morel, originally described by de Candolle and sanctioned by Fries in 1822, Morchella vulgaris, which was recombined by Samuel Gray as a distinct species in 1821 following a forma of M. esculenta previously proposed by Persoon, and Morchella angusticeps, a large-spored species described by American mycologist Charles Peck in 1887. Morchella purpurascens, the purple morel, was first described by Boudier as a variety of M. elata in 1897 based on an 1834 plate by Krombholz, and was recombined as a distinct species in 1985 by Emile Jacquetant. Morchella eximia, a globally-occurring fire-associated species was also described by Boudier in 1910. The old, widely applied name Morchella conica, featuring in many field guides and literature across several countries, has been shown by Richard and colleagues to be illegitimate.

Classification

About 80 species of Morchella were described until the turn of the 21st century, a number of which were later shown to be illegitimate or synonyms. As molecular tools became widely available in the new millennium, a revived interest in the genus commenced and several new species were proposed. In 2008 Kuo described Morchella tomentosa from burned coniferous forests in western North America. In 2010 Işiloğlu and colleagues described Morchella anatolica, a basal species from Turkey later shown to be sister to Morchella rufobrunnea. A study by Clowez described over 20 new species in 2012, while later in the same year, another study by Kuo and colleagues described 19 species from North America. However, several of these newly proposed names later turned out to be synonyms. An extensive taxonomical and nomenclatural revision of the genus provided by Richard and colleagues in 2014, applied names to 30 of the genealogical lineages recognized so far and clarified several synonymities. Also in 2014, Elliott and colleagues described Morchella australiana from sclerophyll forests in Australia, while Clowez and colleagues described Morchella fluvialis from riparian forests in Spain.
In 2015, Loizides and colleagues clarified the taxonomy of Morchella tridentina, a cosmopolitan species described under many names, and recombined Morchella kakiicolor as a distinct species. Later in the same year, Clowez and colleagues described Morchella palazonii from Spain, while Voitk and colleagues described Morchella laurentiana from Canada and Morchella eohespera, a cosmopolitan species present in several continents. In an extensive phylogenetic and morphological study from Cyprus in 2016, Loizides and colleagues added two more Mediterranean species, Morchella arbutiphila and Morchella disparilis, and resurrected Morchella dunensis as an autonomous species. In the same year, Taşkın and colleagues described four of the previously unnamed phylospecies from Turkey: Morchella conifericola, Morchella feekensis, Morchella magnispora and Morchella mediteterraneensis.

Section ''Rufobrunnea''

  • Morchella anatolica
  • *synonym: Morchella lanceolata
  • ''Morchella rufobrunnea''

    Section ''Morchella''

  • Morchella americana
  • *synonyms: Morchella californica, Morchella claviformis, Morchella esculentoides, Morchella populina
  • Morchella castaneae
  • *synonyms: Morchella brunneorosea, Morchella brunneorosea var. sordida
  • Morchella diminutiva
  • Morchella dunensis
  • *synonyms: Morchella esculenta f. dunensis, Morchella andalusiae
  • Morchella esculenta
  • *synonyms: Morchella pseudoumbrina, Morchella pseudoviridis
  • Morchella fluvialis
  • Morchella galilaea
  • Morchella palazonii
  • Morchella prava
  • Morchella sceptriformis
  • *synonym: Morchella virginiana
  • Morchella steppicola
  • Morchella ulmaria
  • *synonym: Morchella cryptica
  • Morchella vulgaris
  • *synonyms: Morchella acerina, Morchella anthracina, Morchella lepida, Morchella robiniae, ''Morchella spongiola''

    Section ''Distantes''

  • Morchella angusticeps
  • Morchella arbutiphila
  • Morchella australiana
  • Morchella brunnea
  • Morchella conifericola
  • Morchella deliciosa
  • *synonym: Morchella conica
  • Morchella disparilis
  • Morchella dunalii
  • *synonym: Morchella fallax
  • Morchella elata
  • Morchella eohespera
  • Morchella eximia
  • *synonyms: Morchella anthracophila, Morchella carbonaria, Morchella septimelata
  • Morchella eximioides
  • Morchella exuberans
  • *synonym: Morchella capitata
  • Morchella feekensis
  • Morchella iberica
  • Morchella importuna
  • Morchella kakiicolor
  • *synonym: Morchella quercus-ilicis f. kakiicolor
  • Morchella laurentiana
  • Morchella magnispora
  • Morchella mediterraneensis
  • Morchella populiphila
  • Morchella pulchella
  • Morchella punctipes
  • Morchella purpurascens
  • *synonyms: Morchella elata var. purpurascens, Morchella conica, Morchella conica var. purpurascens, Morchella conica var. crassa
  • Morchella semilibera
  • *synonyms: Morchella gigas, Morchella gigas var. tintinnabulum, Morchella hybrida, Morchella undosa, Morchella varisiensis, Morchella esculenta var. crassipes, Phallus gigas, Eromitra gigas, Phallus undosus, Phallus crassipes, Mitrophora hybrida, Mitrophora hybrida var. crassipes, Ptychoverpa gigas, Helvella hybrida
  • Morchella septentrionalis
  • Morchella sextelata
  • Morchella snyderi
  • Morchella tomentosa
  • Morchella tridentina
  • *synonyms: Morchella quercus-ilicis, Morchella frustrata, Morchella elatoides, Morchella elatoides var. elagans, ''Morchella conica var. pseudoeximia''